On 07/13/2012 11:54 AM, Dave Jones wrote: > On Fri, Jul 13, 2012 at 08:47:38PM +0200, Thomas Gleixner wrote: > > On Fri, 13 Jul 2012, Dave Jones wrote: > > > > > Looks like calling futex() with garbage makes things unhappy. > > > > WARN_ON(!&q.pi_state); > > pi_mutex = &q.pi_state->pi_mutex; > > ret = rt_mutex_finish_proxy_lock(pi_mutex, to, &rt_waiter, > 1); > > debug_rt_mutex_free_waiter(&rt_waiter); > > > > So there is some weird way which causes q.pi_state = NULL. Dave, did > > you see the warning before the oops happened ? > > No, that didn't seem to trigger.
Well I don't have a fix yet, but I can explain this not triggering. q is on the stack, so the ADDRESS for q.pi_state is never going to be NULL. However, properly instrumented, we do see this: [ 23.621501] ---[ end trace 20bdfb44db182a17 ]--- [ 23.622425] q.pi_state @ (null) [ 23.623272] &q.pi_state @ ffff880185e2dca8 [ 23.624119] ------------[ cut here ]------------ Duh. I'll add a fix to that WARN_ON in my futex-fixes branch along with the fix for the bug Dan found. -- Darren Hart Intel Open Source Technology Center Yocto Project - Linux Kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
